google-cloud-pubsub

A thin wrapper around Google Cloud Pub/Sub for Haskell.

Features

Topic Operations

• Create topics
• Delete topics
• Publish messages to topics

Subscription Operations

• Create subscriptions
• Delete subscriptions
• Acknowledge messages
• Modify acknowledgment deadlines
• Pull messages from subscriptions

Installation

• Cabal: add to your .cabal
  • build-depends: google-cloud-pubsub == 1.1.0.0
• Stack: add to your package.yaml
  • dependencies: - google-cloud-pubsub == 1.1.0.0

This package depends on google-cloud-common for authentication and HTTP helpers.

Usage

Topic Operations

import Google.Cloud.PubSub.Topic

-- Create a topic
result <- createTopic "my-project" "my-topic"
case result of
  Left err -> putStrLn $ "Error: " ++ err
  Right topic -> print topic

-- Publish a message
let message = Message "Hello World" Nothing Nothing
publishResult <- publishMessage "my-project" "my-topic" [message]
case publishResult of
  Left err -> putStrLn $ "Error: " ++ err
  Right response -> print $ messageIds response

-- Delete a topic
deleteResult <- deleteTopic "my-project" "my-topic"
case deleteResult of
  Left err -> putStrLn $ "Error: " ++ err
  Right _ -> putStrLn "Topic deleted successfully"

Subscription Operations

import Google.Cloud.PubSub.Subscription

-- Create a subscription
let config = SubscriptionConfig 
  { topic = "projects/my-project/topics/my-topic"
  , pushConfig = Nothing
  , ackDeadlineSeconds = 600
  , retainAckedMessages = False
  , messageRetentionDuration = Nothing
  , labels = Nothing
  , enableMessageOrdering = False
  , expirationPolicy = Nothing
  , filter = Nothing
  , deadLetterPolicy = Nothing
  , retryPolicy = Nothing
  , enableExactlyOnceDelivery = Nothing
  }

createResult <- createSubscription "my-project" "my-subscription" config
case createResult of
  Left err -> putStrLn $ "Error: " ++ err
  Right subscription -> print subscription

-- Pull messages
pullResult <- pullMessages "my-project" "my-subscription" 10
case pullResult of
  Left err -> putStrLn $ "Error: " ++ err
  Right response -> do
    mapM_ print $ receivedMessages response
    -- Acknowledge messages
    let ackIds = map ackId $ receivedMessages response
    ackResult <- acknowledgeMessages "my-project" "my-subscription" ackIds
    case ackResult of
      Left err -> putStrLn $ "Ack error: " ++ err
      Right _ -> putStrLn "Messages acknowledged"

-- Delete a subscription
deleteResult <- deleteSubscription "my-project" "my-subscription"
case deleteResult of
  Left err -> putStrLn $ "Error: " ++ err
  Right _ -> putStrLn "Subscription deleted successfully"

Authentication

Authentication is handled by google-cloud-common and follows this order:

1. If GOOGLE_APPLICATION_CREDENTIALS is set, a Service Account JSON is used to create a signed JWT which is exchanged for an access token.
2. Otherwise, the Compute metadata server is used (suitable for GCE/GKE).

Dependencies

• google-cloud-common - Common functionality for Google Cloud libraries

License

MIT © Contributors